The most difficult part of installing OpenBSD is deciding how to partition your hard drive. When you don't know how partitions work, choosing a partition layout can be
Partitions are logical subsections of a hard drive. Different partitions can be handled in different ways and can even have different file systems or different operating systems on them. We're going to discuss partitioning for both single-OS and multiple-OS
Get a piece of paper to make some notes about your partitioning. Start by writing down the size of your hard disk. This is the amount of space you have to divide between your partitions. Write down the
Partitioning might seem like a pain; why should you bother? Many commercial operating systems allow you to simply have one large partition over your entire hard disk, giving you a single 80-gig partition. What are the advantages of partitioning?
Different operating systems have different partition types and different requirements for disk layout. A Microsoft operating system simply cannot recognize an OpenBSD disk format and will insist upon formatting it before using it. Although OpenBSD can mount partitions designed for most other popular operating systems, do not put the main OpenBSD system programs on a foreign partition. Let each OS run on its own section of disk. If you want to have multiple operating systems on your machine, you must partition.
But when you're running a dedicated OpenBSD machine, why should you bother to split up your hard drive? On a physical level, different
If you're installing a dedicated OpenBSD machine, you don't have to worry about sharing the hard drive with another operating system. This
The main partitions you'll need to consider are / (root), swap space, /tmp, /var, /usr, and /home. If you forget to create any of these partitions, the installer will put the files that should go in the partitions into your root partition. This will quickly fill up your root partition!
The root partition holds the main system configuration files and the most essential UNIX utilities needed to get a computer into single-
If you're familiar with other some other UNIX-like operating systems, such as some distributions of Linux, you might be used to simply using a single large root partition and
Many old i386 systems have a 504MB limit on hard
Additionally, for some time i386 systems had a similar (not identical) 8GB limit. OpenBSD still obeys that 8GB limit. Even if your system is not susceptible to the 504MB limit, your entire root partition must be completely contained within the first 8GB of disk.
Of course, if you follow my advice and make your root partition 500MB you will never have to worry about either of these restrictions and the potential damage that they can inflict.
If you break these rules, your system will probably appear to work. The second you upgrade your system, or move the file /bsd, the computer will quite probably
So, how much swap space do you need? This is a matter of long debates between
If you find that you need more swap space, you should probably buy more memory instead. If that's not an option, you can use a regular file as a swap file. Still, if you have a reasonable amount of disk space, simply assigning an amount of swap equal to twice the amount of RAM you have is
You should also consider possible future upgrades. If a computer has 500MB of RAM today, but you plan to upgrade it to 3GB of RAM in a couple of months, perhaps assigning 6GB of disk space to swap is a good idea. After all, if you can afford three gigs of RAM and you have the hardware to manage it,
If you have multiple disks, you can vastly improve the efficiency of your swap space by splitting it among multiple drives. Put the first swap partition on the second-outermost ring of the drive with your root partition, and other swap space on the outermost edge of their drives. This
For swap splitting to work best, however, the drives must be SCSI. If you have IDE drives, the drives need to be on different IDE controllers. Remember, each IDE controller splits its total data throughput among all the connected hard drives. If you have two hard drives on the same IDE controller and you're accessing both drives
The /tmp directory is system-wide temporary space. If you do not create a separate /tmp partition, it will be included on your root partition. This means that your system-wide temporary space will be subject to the same conditions as the rest of your root drive. This probably isn't what you want,
Requirements for a /tmp directory are
The /var partition contains frequently changing logs, mail spools, temporary run files, the default website, and so on. If your server is a Web server, your website logs will go to this partition, and you may need to make it 1GB or more. On a small "generic Internet mail/Web server," I'll frequently give /var 20 percent of my remaining disk space. If the server handles only email or databases, I'll kick this up to 70 percent or more, or just assign a space to the remaining partitions and throw everything else I have on /var. If you're really cramped for space, you might assign as little as 30MB to /var. (Again, actual minimum requirements vary depending on your version of OpenBSD.)
The /usr partition holds the operating system programs, system source code, compilers and libraries, and other little details like that. Much of this changes only when you upgrade your system.
On a modern hard drive, I recommend using about 6GB on your /usr partition. This should be more than sufficient for all the contents of /usr and just about any add-on packages you might
The /home partition is where users keep their files. If you have more disk space than is good for you, assign it here. Your home directory will quickly fill up with all sorts of stuff that you'll be tripping across years from now.
The /home partition can easily be the last on your disk; it doesn't need to be fast. It also doesn't need to be large; the only files on the drive will be the ones that you need.
If you've been adding this up, you should notice that it's entirely possible to have a complete OpenBSD system (without the X Window System) in less than 300MB. Just for kicks, compare that to the amount of space a minimal install of Windows XP requires or the size of an minimal Solaris 9 box installation. Your complete install, with all your user programs, may be far larger than 300MB — but all that space is used up because of things you
If you have a second hard drive of comparable quality to your main drive, you can make
In general, segregating your operating system from the data you're serving
If you have no idea what your system will be for, make your second drive /usr and split your first hard drive amongst /var, /tmp, /, and swap space.
If your second drive is much slower than your main system drive, don't bother using it. Not only will its performance be poor, chances are that it is much older than your main drive and far more likely to fail.
If you need to install more than one operating system on your computer, an extra hard drive is an excellent and easy way to do that.